Advanced Micro Devices Inc (AMD)

[morrowinder]

NX bit incompatible with some drivers and applications:

This may explain why Service pack 2 has been delayed so much.

"Driver compatibility issues with data execution prevention mostly center on PAE mode-induced compatibility issues."

"The primary driver compatibility concern is running Physical Address Extension (PAE) mode on 32-bit systems. PAE mode enables processors to address greater than 4 gigabytes (GB) of memory. The primary difference between PAE memory paging and non-PAE memory paging schemes is the extra level of paging that is required in PAE mode (3 levels instead of 2)."

"A final DEP compatibility concern derives from systems with PAE mode enabled, even though they may not be designed for more than 4GB of physical RAM. Microsoft has noticed in testing some systems with processors that support the NX processor feature fail to boot or have other stability issues when the processor is running in PAE mode.

PAE mode is a requirement for leveraging the NX processor feature. Therefore, system designers and firmware engineers should be aware that even though the system’s chipset and firmware may not have been designed to support more than 4GB of physical RAM, the system may be running in PAE mode."





http://www.microsoft.com/technet/prodtechnol/winxppro/maintain/sp2mempr.mspx